This invention relates to railroad cars, and more particularly to a rail car that is extensible and contractible in length to accommodate the carrying of cargo containers of various lengths.
Cargo containers presently are provided in four lengths of 20 feet, 40 feet, 45 feet and 48 feet, and rail cars for supporting them are provided in lengths of 40 feet for supporting one or two 20 foot containers or a 40 foot container; 45 feet and 48 feet for supporting the 45 foot and 48 foot containers, respectively. This necessitates the maintenance of the large inventory of expensive and bulky rail cars, consuming much trackage and badly needed space when not in use. It further requires the time consuming and costly manuevering of such a variety of rail cars in the assembly of a train.
From a practical standpoint, at present moat rail cars are being built and purchased to carry 48 foot containers. However, they most often carry only two 20 foot or one 40 foot or 45 foot containers. Accordingly, the fixed 48 foot length not only creates a train length that is dangerous and annoying to the public at crossings, but it also produces excessive space between cargo containers that contributes adversely to excessive air drag or wind resistance, with consequent consumption of excessive fuel. It also presents a problem of storage of large numbers of 48 foot rail cars.